[Elecraft] KX3 Filter Blow-By

[Oliver Dröse]

Hi Jim,

okay, that's another effect you are experiencing. Sideband suppression on 10 & 6m was really bad on my KX3, too, just about 25 dB on 10 m and 10 dB on 6 m, but that was easily fixed with the OSB suppression by band field test firmware. It is probably going to be officially released soon. It will suppress the OSB by more than 60 dB per band if correctly done, I even have cases where I cannot hear the OSB anymore (seems like a wonder, hi) with an S9+20 main signal.

Luckily I do not experience your 50 Hz signal problem.

73, Olli - DH8BQA


  ----- Original Message ----- 
  From: Jimk8mr at aol.com 
  To: droese at necg.de ; elecraft at mailman.qth.net ; n6kr at elecraft.com 
  Sent: Tuesday, October 09, 2012 2:48 PM
  Subject: Re: [Elecraft] KX3 Filter Blow-By


  I did some more careful checking this morning, transmitting a few watts on the FT-1000MP and using a couple of inches of wire as an antenna on the KX3, on a quiet 10 meter band. The S-meter on the KX3 was 9+

  There is noticeable opposite (lower frequency) side suppression issues, but this cuts off at about 900 Hz

  On the higher side, I can hear signal to as far as my hearing and/or the audio chain permit. The most interesting note was that the undesired signal (high side only) takes a sharp dip or disappears every 50Hz, at .00 or .05 on the frequency readout.

  I'm not sure what to make of all this, but FWIW . . . 


  73   -  Jim  K8MR




  In a message dated 10/8/2012 3:29:37 P.M. Eastern Daylight Time, droese at necg.de writes:
    Hi Jim,

    did you have VFO NR enabled by chance? I suppose yes, as the KX3 is quite 
    unusable on the high bands without. :-( There is a known issue = bad effect 
    of the DSP leading to "artifacts", i.e. hearing signals +/- 5-6 kHz again 
    from strong stations. If you turn off VFO NR it goes away, but then the VFO 
    noise is much too strong. :-( Another bad effect is even with VFO NR enabled 
    if you tune "over" strong stations you suddenly have strong VFO noise until 
    you stop turning the wheel. Afterwards it's gone again. And if you turn the 
    VFO fast enough you will not even recognize even 59+ signals. :-( All 
    problems from the VFO NR DSP implementation as confirmed by Elecraft. And no 
    matter if with or without roofing filter and with/without 8 kHz shift 
    enabled. Still wonder why nobody else is complaining about those effects? 
    Cannot be that everybody has an s4 noise level on 12, 10 & 6 m that would 
    mask the VFO noise and thus no need to enable VFO NR.

    I documented all those effects on video and sent it over to Wayne. He said 
    he and Lyle are working on it, hopefully with some results soon, otherwise 
    the KX3 is of no use for a high band op like me. :-( Never seen such 
    problems with *any* other rig owned so far ...

    73, Olli - DH8BQA



    ----- Original Message ----- 
    From: <Jimk8mr at aol.com>
    To: <elecraft at mailman.qth.net>
    Sent: Monday, October 08, 2012 7:46 PM
    Subject: [Elecraft] KX3 Filter Blow-By


    >A recent KX3 owner (# 1677), I've noticed hearing out of passband  signals
    > from loud CW stations. I can hear such stations up to several KHz  away. I
    > suspect the range is limited by the audio response of the system, 
    > including
    > my ears. Both sides of zero beat, though less so on the opposite side  of
    > the zero beat.
    >
    > In the CA QSO Party this weekend, maybe the loudest 10% of the stations on
    > 10 CW Saturday afternoon were leaking through. (I've heard the leakage on
    > other  bands as well.)
    >
    > I don't have any roofing filters. (I figured any stations weak enough  for
    > me to need the filter to hear, would never be able to hear me anyway).
    >
    > Is this normal, or is there some shielding or other issue affecting my
    > unit? (It is a kit version).
    >
    >
    > 73  -  Jim  K8MR
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